Distribution Of The NOS Positive Nurons In The Pathway Of Visceral Noxious Signals Of Rats

Objective: 1. In order to investigate the distribution of nitric oxide synthase (NOS) in the pathway of visceral noxious signals, we explored the coexistence of NOS and c-fos in the neurons of the rat brain following visceral noxious stimulation. 2. To estimate the effect of the NO on the amygdaloid complex (AMC), we studied the origin of the NOS positive fiber terminals in the medial amygdaloid nucleus (Me) . methods: 1.We used double staining immunocytochemical techniques to determine whether colocalization of NOS and c-fos immunoreactivities induced by noxious visceral stimulation in the neurons of the rat. 2. Noergic afferent projection to Me were identified by a combined retrograde CTb immunocytochemical and NADPH-d histochemical staning method after microinjecting CTb into Me. Results: By the method 1, the double labeled neurons(NOS/c-fos) were observed in solitary nucleus, dorsal raphe nucleus, paraventricular thalamic nucleus, medial parabrachial nucleus, medial habenular nucleus, ventrolateral part and dorsolateral part of periaqueductal gray, paraventricular hypothalamic nucleus, periventricularhypothalamic nucleus, medial amygdaloid complex, dorsomedial hypothalamic nucleus. By the method 2, the double labeled neurons(NOS and CTb) is located in locus ceruleus, dorsal raphe nucleus, the basolateral amygdaloid nucleu, parabrachial nucleu, ventrolateral part of periaqueductal gray. Conclution: l.This anatomical finding suggested that c-fos and NADPH-d double labeled neurons described above are distributed in the pathway of visceral noxious stimulation and NO as a neurotransmitter is playing a important role in the processing of visceral noxious signals. 2. NOS positive fiber terminals in the Me is main come from locus ceruleus, dorsal raphe nucleus, the basolateral amygdaloid nucleu, parabrachial nucleu, ventrolateral part of periaqueductal gray.